Machine for sharpening lawn-mower blades



Nov. 23 1926.

H. YERKEY MACHINE FOR'SHARPENING LAWN MOWER BbADES 7, 1922 5 Sheets-Sheet 1 Filed Sept ATTORNEY INVENTOR WITNESSES Nov. 23 1926. 1,608,013

H. YERKEY MACHINE FORJSHARPENING LAWN MOWER BLADES Filed Sept. '7, 1922 5 Sheets-Sheet 2 II!llllIlllllilfilllllllllllllllllllllllllll i INVENTOR ATTORNEY Nov. 23 1926. 1,608,013

H. YERKEY MACHINE FOR SHARPENING LAWN MOWER BLADES Filed Sept. 7, 1922 5 Sheets-Sheet 5 INYENTOR WITNESSES A-rroRNEY Nov. 23 1926.

H. YERKEY MACHINE FOR SHARPENING LAWN MOWER BLADES Filed Sept. 7, 1922 5 Sheets-Sheet 4 m g w) w w p F ,rvw u 47 m J. m m Q f g fimry Mar/r I N V E NTO R ATTORN EY WITNESSES Nov. 23

H. YERKEY MACHINE FOR SHARPENING LAWN MOWER BLADES Filed Sept. 7, 1922 5 Sheets-Sheet WITN ESSES ATTOR N EY Patented Nov. 23, 1926.

HENRY YERKEY, or v IoLA, ILLINOIS.

MACHINE FOR SHARPENINGLAWN-MOVER BLADES.

Application filed September 7, 1922. Serial No. 586,687.

This invention relates to improvements in machines for sharpening lawn mower blades and its general objects are to provide a machine which can be accurately adjusted and easily operated and by which the blades of a lawn mower may be quickly sharpened.

Other objects of the invention will appear from the following description.

In the accompany ng drawings wherein is P shown for illustrative purposesa preferred embodiment of the invention,

Figure 1 is a plan view of a machine constructed in accordance with the invention; Fig. 2 is a front elevation of the same; Fig. 3 is a vertical transverse section; Fig.4 is a rear elevation; r Figs. 5 and 6 are respectively a plan view and sectional elevation of the mechanism for changing the direction of travel of the slide rest;

Fig. 7 is a plan of one of the bevel gears used in the mechanism of Figs. 5 and 6;

I employed for holdingthe cutter bar; and

of oneof the cut-' Fig. 12 is an elevation ter bar clamps. Referring more specifically to the illustrative embodiment of the invention shown.

in the drawings, and first particularly to Figures 1 and 2, the machine there shown includes a main frame 15 of any convenient construction, but preferably of the knockdown type and supporting a pair of horizontal longitudinally extending and parallel slideways 16. The slideways 16 are prefer- .ablymade from square steel bars so supported as to present two inverted V-shaped' tracks upon which slide rest 17 may travel. The slide rest is shown in vertical section and on a larger scale in Fig. 3. 'It consists of a-main block analogous to a slide rest on a lathe having slides 18 designed to contact with thejtrack surfaces of the ways 16. Guides 19 are attached to the slide re'stand extend downwardly-- to hold the "slide rest upon the ways. 4 I l The upper side of the slide rest has two naled in the frame 'wardly parallel plates 20 whose facing edges are beveled as indicated in Figure l; and a plate 21 having cooperating beveled edges is mounted between the parallel guiding plates 20. Thus, while the slide rest is movable longitudinally of the machine, the plate 21 is movable transversely thereof. The outer end of plate 21 preferably has a depending lug'or ear 22 (Fig. 3) secured to a transverse adjustment screw 23 near the knurled head 24 thereof. The adjustment screw 23 passes through a threaded bore provided within the slide rest 17 so that longitudinalmovements of the screw 23 will adjust the position of the plate 21.

At the rear of the slide rest, as shown in Fig. 3, there is secured a depending bar 25 uponthe lower end of which isfulcrumed a lever26. v carries a depending guide 27 for the lever and a dog 28 on the lever is engageable with notches provided in the guide 27 so that the lever 26 may be held in either of two positions. At an intermediate point on the lever, a half nut 29 is pivotally mounted. The half nut 29 has vertical bores adapted to receive a pair of parallel guide pins 30 extending beneath aboxing 31 secured to the under side of slide rest 17. A longitudinally extending feed screw 32is jour- 15 midway between the slideways 16 but beneath the same; and the'boxing 31 is cut away to permit the slide rest to move along the slideways without interference from the feed screw. hen it is desired to drive the slide rest bythe rotating screw 32, the lever 26 is moved upuntil the dog 28 engages with the upper notchof the guide 27, whereupon the half nut 29 is brought into engagement with the feed screw '32; and the sliderest will then move in one direction or the other according to the direction of rotation of the feed screw.

The feed screw 32 is driven preferably by means of an electric motor 33 mounted on the machine frame, which also is utilized to drive the other parts of the machine, as will be described later. The; motor pulley 34 drives he pulley '36 which is fast upon shaft 37 by means of a belt-35. See Fig.4.

Shaft87 also mounts pulley 38-driving; pulleyAO on a shaft 4:1 bvmeans of a belt 39. A bevel gear 12 on shaft 41; meshes with a bevel gear 43' on "shaft 43 at the other end of wwhich -another bevel gear 4A: jisjloosely :2.

mounted. Referring now particularly to Figs;' 5, 6 and 7, it is seen that the bevel gear 44 meshes with gear mounted on one end of the feed screw 32. The Shaft 43 carries a second loose bevel gear 44 also meshing with gear 45; and the two bevel gears 44, 44 have pins projecting from the inner faces thereof (Fig. 7) which are adapted to be engaged with a clutch so that one or the other of the bevel gears will drive the feed screw and hence change the direction of rotation of the same. Upon the frame 15 a bracket 46 is secured and supports a lever 48 swingable about a pivot pin 49. The lever 48 is preferably circular atits pivoted end as shown at 48. The plate 47 is mounted to swing about the pivot pin 49 above the circular part 48 and a post 50 is secured at one end of plate 4?. Upon the post 50 is a C -shaped arm 50" having means for engagement with the double clutch member 5l so as to slide the clutch along shaft 43? when the plate 47 is swungabout its axis. It will be understood that the clutch 51 rotates with the shaft on which it slides. A pin 52 is secured in the lever end 48' to extend both above and below the same, the plate 47 having an arcuate slot- 53 adapted to pass the pin while the bracket 46 has a similar but longer slot 46. To the lower end of pin 52 a spring 54 is attached and at the other end the spring is secured to the machine frame. The function of the spring 54 is to maintain the lever 48. in a neutral position wherein the clutch members 51 and 51 are out of eiigagement with the pins and bevel gears 44 and 44?. Obviously, when the lever 48 is'swung in either direction against resistance of spring 54 the slidable rotary clutch will be brought into engagement with a bevel gear causing rotation of the feed Screw in the required direction.

lVhile the above described means for changing the direction of rotation of the feed screw 32 is the one I prefer, .i will be understood that various other well known mechanisms for effecting the same purpose might be'e'mplo'yed.

The parts for supporting the rotary cut ter of a lawn mower during the sharpening operation will now be described.

The plate 21 of the slide rest Lngitudin'ally extending bar 55 by a bolt'or the like 56 pass i tral herein the bar, the a: such that the 55 may sell. zontal plane about the bolt as s.

o bar 55 a cured to or inte l with V mid point 18 an arm 5? e: nding at right I 'lngle's to' the bar 55 having head 58in wuch slot 59 1s provided. A vertical pm BOeXtends upwardly from plate 21 through the slot59 and at'each'side of the head 58 there is" a thumb screw 61" adapted to el te" slot59 and bear against pin 66. As the arm 57 is rigidly connected to bar 55, it will be clear that the latter may be swung about bolt 56 as an axis and be maintained in the desired position by turning the thumb screws 61 into engagement with pin 60.

The bar 55 slidably mounts a pair of upright posts 62 and clamps 63 carried on said posts provide means whereby the posts may be held in the desired positions along the bar 55. The clamps are best shown in Fig.

8. On the upper ends of the posts 62, the

clamps for supporting lawn mower reels are mounted. These clamps preferably each include a stationary bar 64 secured to the post 62 and av movable bar 65 adjusted toward or from the stationary bar 64. Upon bar 64 a bolt 66 is mounted and the movable bar 65 is supported a shoulder provided at the upper end ofsaid bolt. Nut 661" on the upper endofbolt essay be used to force the bar 65 downwardly, while the screw 67 passing through bar 65 and hearing at its lower end against bar64 is used to force the outer ends of the two bars apart, hence the inner ends together. As seen in Fig. 3, the bars 64 and 65 have meeting notched inner ends adapted to hold the cutter shaftwhilc permitting rotation thereof.

It will be clear that the positions of the posts 62 may be changed to accommodate any length of a rotary cutter while the clamps 64, 65 will hold against rotation any size of cutter shaft. At the same time, the bar 55 may be swung in a horizontal plane causing like movement on the part of tie rotary cutter; and as the bar 55 is mounted on the slide rest, it may move transversely of the machine and also travel longitudinally of the machine in either direction.

Fig. 9 shows mypreferred meansfor supporting a'ball'bearlng lawn mower reel so that the bearings are retained in position. The shaft 68 of the reel 69 is passed through a hollow centering member 70 whose inner endis'conical as indicated at 71 so as to permit the centering member to enter the ball race 72. The centering member has an annular flange 73 and astub shaft or collar 74,'the latter being provided so that the clamps '64, 65 may grip the centering member, with flange 73 bearing against the clamp ends. The reel may then be ro tatedi'reely. I r

The blade grinding or .siarpen n will now he described;- be had par" yicnlarly to if Upon the main port for plurah 1 said support preierably comp ard 75' mounting bearings '76 for 1a I The'shaft may be driven by a belt? 8 passing a'roui-id pulley 79011 shaft- 77 and over puliev 80 on the main shaft 37/ The bearings are provided on ail-arm 76. mounted; to. swing on standard 7 5 about a bolt 7 6 as an axis. This bolt may be used to hold the shaft 7 7 in various adjusted positions, and hence adjust the positions of the grinding wheels-.81, 82 which are fast upon opposite ends of shaft 7'7. The grinding wheels preferably are both emery .wheels, and the periphery of emerywheel 81 is preferably beveled while emery wheel 82 is of the ordinary circular form. I contemplate using emery wheel 82 for grinding the blades of the rotary cutter of lawn mowers, and wheel 81 for grinding the straight cutter bar; and the pivotal mounting of arm 76 permits the wheel 81 to be swung and locked in such position (about one quarter of a turn) that its periphery engages the cutter bar at the proper angle, as snown clearly in Fig. 10. In order to hold belt 7 8 in driving position when the arm 76 is so turned, a vertical idler pulley 83 is mounted on arm 76.

W hen arm 7 6 is turned, the effect will be to twist the belt 78 and thus shorten its effective length. The standard is mounted on the machine frame so that it can be raised slightly to compensate for the tightening of the belt.

It will be recalled that the reels or rotary cutters are supported on the machine by their shafts so that they are freely rotatable.

Inorder to hold the spiral blades of such cutters against the grinding surface of wheel 82 whereby the proper beveled edge will be ground throughout the length of said blades, the blade holder best shown in Fig. 10 is employed by preference. It consists of a slotted adjustable block 84: carrying a rod 85 near its outer end and supported upon the under side of arm 7 6. Theupper end of rod 85 has guide member 86 shaped like an arrow head, and the spiralblades are turned by contact with-either of the-slanting sides of guide member 86 so that the desired cutting edge is ground throughout the length of the spiral blades. The rod 85mounts a sec-.

ond adjustable block 87, held by a: set screw or the like, and a bar 88 is rigidly attached to block 8'? and extends upwardly. Pivoted on-bar 88 is a blade holder 89 pressed downwardly against the apex of .block 86 by means of spring 90. The spiral blades of the mower are interposed between holder 89 and member 86 before the grinding is started, and the blocks 84: and 87 are independently adjusted to insure contact of the blades and emery wheel.

The holder for the straight cutter bar during the grinding operation now remains to be described. See Figs. 10,11 and 12. This holder is preferably in the form of a separate attachment, comprising a rod 91 having reduced ends 92 adapted to "enter sockets or holes 93 (Fig. 3) in the posts 62 so that the rod'm'ay be rocked about its axis, aswill be understood from Fig. 10. To at Turning the wheel 96 forces the ledger blade 103 against the beveled grinding wheel 81.

There are two or more blade clamps mounted on rod 91, one of'which is shown separately in Fig. 12. It includes an arm 97 rigidly secured to rod 91 and having a clamping screw 98 at its outer end. An arm '99 is held in adjusted relationship to arm 97 by means of a threaded rod 100 secured to .the latter arm. Obviously when rod 100 is turned rm 99 will be moved toward or from arm 97. A clamping screw 101 is at the outer end'of arm 99 which is somewhat shorter than arm 97. The point of screw 101 is between the point of screw 98 and aprojection 102 on arm 97 whereby the blade 103 (Fig. 10) may be clamped firmly between the two arms.

The other blade clamp is constructed.

similarly to the one shown in Fig. 12 ans like parts are similarly designated except 10 1 has flanges 1041 at opposite ends, and an ad usting screw 105 passes through the upper flange 104* to engage with extension 103, while a spring 106 mounted on extension 103 bears against the lower flange 10 .9. The tendency of spring 106 is obviously to move extension 103 upwardly or in a counterclockwise direction, and the arm 97 downwardly, while screw 105 when turned downwardly will increase the tension of'spring 106, andwill cause the blade 103 to be held more forcibly against the emery,

wheel 81. In other words, the spring 106 opposes the screw 105 in leveling the ledger blade.

The foregoing is a description of a pre- 1 ferred embodiment of theinvention but it will be clear that the invention is not limited to the showing of the drawing and that many changes involving;omission, substitution, alteration or reversal of parts may be made without departing from my invention,

which is best delinedin the following claims.

What is claimed 1s;- j v I 1. Ina lawn mower sharpening machine,

a frame, a grinding wheel on the frame, 1

reciprocating carriage guided for movement parallel to the axis of the Wheel, a cutter bar support pivotally mounted for angular adjustment with respect to the movement of said carriage, a cutter bar carrier mounted for turning movement in said support, said support and carrier being laterally movable toward and away from said grinding Wheel, means for turning said carrier in said support including a worm gear on the support and a Worm on the carriage, and means for holding the cutter bar against the grinding Wheel and comprising a resilient element permitting adjustment of the cutter bar With reference to the grinding Wheel.

2. In combination with a grinding Wheel, a rod, a ledger blade clamp mounted on said rod and having means for clamping a ledger blade in proper relation to the grinding Wheel, said blade clamp being pivoted on said rod and having an extension, a set screw at one side of the extension fixed with respect to said rod and providing a stationary stop, and a spring on the opposite side of said extension operatively arranged between it and a stationary abutment also fixed to said rod to hold said extension yieldingly against said screw, aid screw and spring adapted to maintain the blade in contact with the grinding means.

In testimony, that I claim the foregoing as my own, I have hereto aiiixed my signature. V

HENRY YER-KEY. 

